We propose the rapid decline of CBP and associated histone acetyltransferase (HAT) activity during maturation serves the function of ending a series of critical periods of organization, especially in the brain, but by reducing transcriptional flexibility leads to a loss of adaptive capacity during aging. We demonstrated significance of the protective effect of the CBP complex during aging in studies showing that this complex is induced by dietary restriction and that blocking this induction blocks several protective effects of dietary restriction. We therefore propose to examine in more detail mechanisms by which CBP functions as a juvenile protective factor whose depletion after maturation drives age-related impairments. I. Causes and consequences of decline in CBP-HAT activity during maturation. Specific lipids after weaning reduce the rapid reduction of CBP during maturation. We therefore propose to assess mRNA of CBP and other transcription factors or histone acetylation in several brain areas liver, and jejunum from male and female mice at birth, and 1, 2, 3, and 4 weeks after birth;mice will be weaned either to a normal high carbohydrate diet or a high-fat diet, Since HDAC inhibitors can compensate for reduced HAT activity, and we have shown that HDAC inhibitors increase lifespan and improve some age-related impairments, an additional group of mice will be treated with an HDAC inhibitor. II. Long-term consequences of diet during maturation Breastfeeding produces long-term health benefits possibly mediated by lipids in milk. We therefore propose to assess if weaning mice onto a diet high in specific lipids until 3 months of age will produce permanent elevation in the CBP transcriptional complex with concomitant improvement in histone acetylation and adaptive capacity (memory, rhythms, and response to nutritional deprivation) during aging. III. Reversal of age-related impairments by HDAC inhibitors 6- and 16-month-old mice will be treated with HDAC inhibitors for 2 months and histone acetylation and memory, rhythms, and response to nutritional deprivation will be assessed. We anticipate that weaning to a diet high in lipids and treating with HDAC inhibitors will cause improve histone acetylation and adaptive capacity during aging. The proposed studies involve assessing if two interventions, post-weaning to a high-fat diet, and a drug that we have shown to be protective in a model organism, will have a protective effect during aging. If successful human trials may ensue.